Lysosomes and Cathepsins (IMAGE) Georgia Institute of Technology Caption The cathepsins in the study were cysteine cathepsins and are best known for their work in the lysosome, a cell organelle, where they break down unneeded proteins into amino acids. Credit National Institutes of Health Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.